Fluid propelled mine haulage vehicle and method for underground haulage

ABSTRACT

The underground mine haulage vehicle is particularly adapted for use as a shuttle vehicle between a continuously advancing loading station and a fixed discharge station to transport material dislodged by the continuous mining machine at the loading station to fixed conveying apparatus at the discharge station. The mine haulage vehicle has a mobile body with pairs of front and rear traction wheels. A fluid actuated motor is connected through suitable driving connections to the traction wheels. Accumulators having fluid under pressure therein are connected to the fluid actuated motor and the fluid under pressure from the accumulators actuates the fluid motor and propels the shuttle vehicle. The fluid circuit includes a fluid inlet connection to the accumulators and a fluid outlet connection from a reservoir. At a recharging station located adjacent to the fixed discharge station a suitable recharging device is provided for recirculating the fluid from the reservoir to the accumulators and compressing the gas in the accumulators to recharge the accumulators with fluid under pressure. Other embodiments include providing a pump on the haulage vehicle to transfer the fluid from the reservoir to the accumulators and recharging the accumulators with fluid under pressure. A separate electric motor for the recharging pump is located adjacent the fixed discharge station and is connected thereto to energize the pump while the vehicle is discharging the dislodged material. In another embodiment the fluid actuated motor is also operable as a pump to transfer fluid from the reservoir to the accumulators. A separate circuit may be provided from the external recharging means to a drive motor for the conveyor so that the conveyor may be driven by the external recharging means while the fluid system is being repressurized.

Elite Jamison States Patent [54] FLUID PROPELLED MINE HAULAGE VEHllCLEAND METHOD FOR UNDERGROUND HAULAGE [56] References Cited UNITED STATESPATENTS 2,578,959 12/1951 Yarborough ..60/5l 3,556,013 1 1971 Kruer..104 157 FOREIGN PATENTS OR APPLlCATI ONS 510,861 3 1955 Canada..105/65 Primary Examinen-Albert J. Makay Attorney-D. Leigh Fowler, Jr.et al.

[57] ABSTRACT The underground mine haulage vehicle is particularlyadapted for use as a shuttle'vehicle between continu- I ously advancingloading station and a fixed discharge station to transport materialdislodged by the continuous mining machine at the loading station tofixed conveying apparatus at the discharge station. The mine haulagevehicle has a mobile body with pairs of front and rear traction wheels.A fluid actuated motor is connected through suitable driving connectionsto the traction wheels. Accumulators having fluid under pressure thereinare connected to the fluid actuated motor and the fluid under pressurefrom the accumulators actuates the fluid motor and propels the shuttlevehicle. The fluid circuit includes a fluid inlet connection to theaccumulators and a fluid outlet connection from a reservoir. At arecharging station located adjacent to the fixed discharge station asuitable recharging device is provided for recirculating the fluid fromthe reservoir to the accumulators and compressing the gas in theaccumulators to recharge the accumulators with fluid under pressure.Other embodiments include providing a pump on the haulage vehicle totransfer the fluid from the reservoir to the accumulators and rechargingthe accumulators with fluid under pressure. A separate electric motorfor the recharging pump is located adjacent the fixed discharge stationand is connected thereto to energize the pump while the vehicle isdischarging the dislodged material. In another embodiment the fluidactuated motor is also operable as a pump to transfer fluid from thereservoir to the accumulators. A separate circuit may be provided fromthe external recharging means to a drive motor for the conveyor so thatthe conveyor may be driven by the external recharging means while thefluid system is being repressurized,

7 Claims, 8 Drawing Figures PATENTEDJAN 23 I975 SHEET 2 BF 3PATENTEDJAHZB I975 3.712.489

sum 3 or a FLUID PROPELLED MINE IIAULAGE VEHICLE AND METHOD FORUNDERGROUND HAULAGE BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to a fluid propelled haulage vehicleand method for underground haulage and more particularly to a fluidpropelled haulage vehicle in which an external source of power isemployed to pressurize the fluid.

2. Description of the Prior Art Shuttle type mine haulage vehicles foruse in underground haulage systems are well known. The conventionalpropulsion systems associated with the underground haulage vehicles areelectric motors supplied with current through a trailing cable. U.S.Pat. Nos. 2,953,213 and 2,925,136 disclose haulage vehicles with asingle electric motor to drive all of the traction wheels. The currentis supplied to'the electric motor through a cable wound on a cable, reelmounted on the haulage vehicle. The cable is connected at its free endto a power supply usually located between the fixed conveying apparatusand the continuous mining machine. As the haulage vehicle shuttlesbetween the mining machine and the fixed conveying apparatus, the cableis wound on and off 'the cable reel. The trailing cable is a source ofinherent danger in underground mining operations and is frequentlydamaged by the mine haulage vehicles and other external sources.Trailing cables have, in the past, caused underground fires due to a,cable parting while current is flowing therethrough.

In order to eliminate the inherent danger of the trailing .cables, ithas been proposed to provide internal combustion engines as illustratedin US. Pat. No. 3,067,830 as the propulsion means for the haulagevehicles. lntemal combustion engines, however, discharge objectionableexhaust fumes and, even with elaborate scrubbing apparatus, have notbeen accepted for underground use in coal mines.

' Another alternativethat has been proposed is the use of storagebatteries on the haulage vehicle. Because of the power requirements, thesize of the storage batteries to carrya sufficient amount of electricalenergy on the haulagevehicle for a working shift is not practical withthe present day technology of storage batteries. Further, the batteriesdischarge relatively rapidly and require a slow recharging so that it isnot practical to attempt to recharge the storage batteries during thehaulage cycle.

traction wheels connected thereto. A fixed recharging meansisconnectable to the pressure means on the vehicle and is arranged torepressurize the fluid in the fluid storage means.

The haulage vehicle of this invention is thus propelled by fluid underpressure. The fluid under pressure is stored in suitable accumulatorsmounted on the haulage vehicle. A fixed recharging device is positionedadjacent the fixed conveying apparatus and is arranged to rapidlyrepressurize the fluid in the accumulators. In one species of theinvention the pressurized fluid is exhausted from the fluid actuateddrive motor into a reservoir. The recharging device includes a pump thattransfers the fluid from the reservoir to the accumulator where thefluid is repressurized. In another embodiment of this invention thetransfer pump is positioned on the haulage vehicle and is connected to afixed, external power source at the fixed conveying apparatus. With thisarrangement, the energy expended by the haulage vehicle in shuttlingbetween the fixed conveying apparatus and the mining machine is rapidlyreplaced at the fixed conveying apparatus while the haulage vehicle isdischarging the dislodged material There is a need, therefore, for ahaulage vehicle propulsion means that will rapidly replace the energyused during one or more haulage cycles.

SUMMARY OF THE INVENTION The hereinafter described invention includesamine haulage vehicle that has a mobile body with a material haulagecompartment. Pairs offront and rear wheels are arrangcd to propeltthemine haulage vehicle and are connected by suitable driving connectionsto a fluid actuated drive means mounted on the mobile body.

Fluid storage means are mounted on the vehicle and connected to thefluid actuated drive means. Pressure means are provided to convey thefluid under pressure from the fluid storage means to the fluid actuateddrive means to drive the fluid actuated drive means and the from thehaulage compartment onto the fixed conveying apparatus or a conveyorfeeder located at the fixed discharge station. The method forunderground haulage between a continuously advancing loading station anda fixed discharge station includes providing fluid under pressure topropel the haulage vehicle and recharging or repressurizing the fluid to-a preselected pressure at the fixed discharge station.

Accordingly, the principal object of this invention is to provide ashuttle type haulage vehicle wherein the energy expended in transportingdislodged material from a mining machine to a fixed conveying apparatusis rapidly replaced while the haulage discharges the dislodged materialfrom the haulage compartment.

Another object of this invention is to provide a haulage vehicle for usein underground mines that does not require a trailing cable or aninternal combustion engine.

. i BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic top planview of a mine haulage vehicle illustrating schematically portions ofthe drive train for the traction'whe'els and the circuit for thepressurized propelling fluid. I

FIGL'Z is a view in side elevation of the haulage vehicle of FIG. 1taken along the line 11-11 and illustrating the coupling mechanism ofthe recharging apparatus.

FIG. 3 is a top plan view of the fluid pressure recharging apparatus.

FIG. 4 is a view in side elevation taken along the line lV-IV 'of FIG.3.

FIG. 5 is a schematic top plan view similar to FIG. 1 illustratinganother embodiment'of the fluid propulsion apparatus for the haulagevehicle.

FIG. 6 is a schematic top plan view of another embodiment of the fluidpropelled haulage vehicle in which the fluid transfer pump is positionedon the haulage vehicle.

These and other objects and advantages of this inv FIG. 7 is a schematicplan view of another embodiment of the fluid propelled haulage vehiclein which the fluid actuated drive includes a pump for transferring thefluid from the reservoir to the accumulator.

FIG. 8 is a top plan view of a fluid propelled hydraulic vehicle similarto FIG. 1 illustrating another embodiment in which the fluid istransferred from one accumulator to another and gas under pressure issupplied to the fluid system at the recharging station.

The several features of the invention as illustrated in the drawings areembodied in a mine haulage vehicle commonly referred to as a shuttlecar" designed for use in transferring dislodged material in undergroundmines. Reference may be made to US. Pat. No. 2,925,136 for a completedescription of the vehicle construction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The mine haulage vehicleincludes a mobile body generally designated by the numeral 10. There isa longitudinal centrally located material haulage compartment 12 in thebody portion. The mobile body is mounted on pairs of traction wheels 14and 16 that are preferably both traction and steering wheels. An endlessconveyor generally designated by the numeral 18 extends along the bottomof the haulage compartment and includes side chains to which transverseconveyor flights 20 are connected. The side chains are suitablyconnected to sprockets mounted on transverse end shaft 22. The shaft 22is, in turn, driven by a hydraulic motor 24 so that upon rotation ofshaft 22 the endless conveyor 18 moves along the bottom of the materialhaulage compartment 12 and discharges the dislodged material therefrom.Although not illustrated in detail, the body portion 10 includes atiltable boom member 26 which is arranged to pivot and vary the heightof the endless conveyor 18 while discharging dislodged materialtherefrom. Suitable controls are provided to pivot the boom member 26.

In FIG. 1 pairs of wheels 14 and 16 are driven by a fluid actuated motorgenerally designated by the numeral 28. A pair of longitudinal outputshafts 30 and 32 are connected to a gear type reducer 34 which, in turn,has its input shaft connected to the output shaft of the fluid actuatedmotor 28. The shafts 30 and 32 are connected to differentials 36 and 38adjacent the wheels 14 and 16 on one side of the haulage vehicle. Shafts40 and 42 connect the outputs of differentials 36 and 38 to the adjacentwheels 14 and 16. Transverse shafts 44 and 46 extend from thedifferentials 36 and 38 beneath the haulage compartment to the wheels 14and 16 on the opposite side of the haulage vehicle. With thisarrangement, a single prime mover, i.e., the fluid actuated motor 28provides tractive forces for all of the wheels 14 and 16 through thepreviously described driving connections.

The fluid actuated motor 28 may be any suitable hydraulic motor that iscapable of converting hydrodynamic energy into mechanical energy forpropelling the haulage vehicle at desired preselected speeds. Forexample, it has been found that a variable volume type fluid motormanufactured by the Sunstrand Corporation and designated Number 24Series having a displacement of 7.24 cubic inch per revolution has beenfound suitable. The variable volume fluid motor includes a wobble orswash plate that is manually positioned. The angle of the swash platedetermines the volume of oil displaced and in turn controls the speed ofthe vehicle. The swash plate construction permits reversal in directionof the output shaft so that the vehicle may be propelled in either theforward or reverse direction by the fluid actuated motor 28. The speedof the fluid actuated motor is related to and regulated by the torquedemand on the motor. The speed and torque is regulated by the cam andswash or wobble plate. The fluid actuated motor can be reversed toprovide regenerative hydraulic braking for the vehicle by functioning asa pump and pumping oil into the accumulators. It is believed that thefluid actuated motor is more efficient than a conventional DC electricmotor because of the absence of line resistance in the hydrauliccircuit. It should be understood, however, that other suitable fluidmotor devices actuated by fluid under pressure may be employed. Aunidirectional motor may be employed with a mechanical transmission forcontrolling both direction and speed. For example, the transmissionemployed in the haulage vehicle illustrated and described in U.S. Pat.No. 2,925,136 may be employed with a unidirectional fluid actuatedmotor.

The motor 28 has a inlet 48 connected to a fluid conduit 50. The conduit50 is, in turn, connected to the outlets 52, 54 and 56 of accumulators60, 62 and 64. The accumulators 60, 62 and 64 are of conventionalconstruction in i which there is an expandable diaphragm separating agas chamber from a fluid chamber. The accumulators 60, 62 and 64 mayalso be of the free piston type. Although only three accumulators areillustrated, it should be understood that a greater number or lessernumber may be employed depending on the desired amount of fluid that itis intended to store under pressure. When fluid is pumped into theaccumulators 60, 62 and 64, the gas in the gas chamber portion of theaccumulators is compressed to exert a pressure on the fluid within theaccumulators. The fluid under pressure from the gas within theaccumulators 60, 62 and 64 flows through conduit 50 to the inlet 48 offluid motor 28. The fluid motor 28 has an outlet 66 to which outletconduit 68 is connected. The fluid discharged from the motor 28 flowsthrough conduit 68 to an inlet 70 of reservoir 72. Thus the fluid storedunder pressure in accumulators 60, 62 and 64 flows through conduit 50 tomotor 28 where the fluid pressure is converted to mechanical energy andthe fluid flows from motor 28 through conduit 68 to reservoir 72 whichis vented to the atmosphere.

To replace the energy dissipated by the fluid in propelling the haulagevehicle, there is provided a recharging device generally designated bythe numeral 74 illustrated in FIGS. 3 and 4. The recharging device 74may be mounted on suitable propelling devices as, for example, endlesstracks and is preferably positioned adjacent to the fixed conveyingapparatus. The recharging device 74 is connectable at that location tothe fluid circuit of the haulage vehicle as later described to replacethe energy expended during the haulage cycle. The recharging is donewhile the haulage vehicle is discharging dislodged material therefrom atthe discharge station. The recharging device 74 includes an electricmotor 76 connected to a high output positive displacement pump 78. Thepump 78 has a fluid inlet 80 and a fluid outlet 82 as illustrated inFIGS. 3 and 4. An outlet conduit 84 is connected at one end to the pumpoutlet 82 and at the other end to a coupling 86. An inlet conduit 88 isconnected at one end to the coupling 86 and at the other end to a pump89. The pump 89 is, in turn, connected to a tank or reservoir 90. Thetank outlet is connected by a conduit 91 to a priming pump 93. Thepriming pump is connected by a conduit 92 to the inlet of output pump78. With this arrangement the motor 76 is arranged to transferapproximately 130 gallons per minute of fluid from the inlet conduit 88to the outlet conduit 84 through an auxiliary pump 89, reservoir 90 andpriming pump 93. The coupling 86 and the conduits associated therewithare movable transversely on the recharging device body portion 94 andare also arranged to move vertically thereon.

Referring again to the haulage vehicle 10, there is a female coupling 96that has an outlet 98 with a suitable check valve therein connected toconduits 100 and 102. The conduit 100 extends into the reservoir 72 andterminates adjacent the bottom portion thereof. The conduit 102 isconnected to the outlet port 104 of hydraulic motor 24. The femalecoupling 96 on the haulage vehicle has an inlet port 106 with a suitableone-way check valve therein. The inlet port 106 is, in turn, connectedto conduit 108 that is arranged to convey fluid into the accumulators60, 62 and 64 from the coupling 96. There is provided a branch conduit110 connected at one end to the conduit 108 and at the other end to theinlet port 112 of conveyor drive motor 24. A manually operable valve 114is positioned in branch conduit 110 and is arranged to control the flowof fluid therethrough.

QPERATION The above described fluid propelled haulage vehicle 10 may beoperated in the following manner. The gas in accumulators 60, 62 and64is displaced by a fluid, preferably a liquid, for example, hydraulicfluid so that k the fluid within accumulators 60, 62 and 64 is under apreselected speed with the shuttle car. The rotation of the output shaftof motor 28 is transmitted through gear type reducer 34 to the tractionwheels 14 and 16. The fluid exhausted from the motor 28 flows throughoutlet 66 into outlet conduit 68. The fluid is discharged from conduit68 into reservoir 72 that is vented to atmosphere.

After the haulage vehicle 10 has traveled to the continuous miningmachine and the material haulage compartment is filled with dislodgedmaterial, the shuttle car is propelled by the fluid under pressure tothe discharge station where the'fixed conveyor apparatus is located. Atthe discharge station the haulage vehicle 10 is stopped adjacentto therecharging device 74 as illustrated in FIGS. 3 and 4.'Suitable controlsare provided on the rechargingdevice 74 to move the coupling 86 towardthe female coupling 96 on the haulage vehicle 10. When the interfaceportions of the couplings are aligned vertically, the coupling device 86is moved upwardly and connected to the female coupling 96 on the haulagevehicle 10. The motor 76 is energized to withdraw the fluid from thereservoir 72 through conduit and to convey the same fluid under pressurethrough conduit 108 to the accumulators 60, 62 and 64 where the fluiddisplaces the gas within the accumulators 60, 62 and 64 and the gasunder pressure again exerts a pressure on the fluid.

Simultaneously, a portion of the fluid flowing through conduit 108 isdiverted by means of valve 114 into conduit to drive the conveyorhydraulic motor 24 and thus actuate the endless conveyor 18 anddischarge the dislodged material from the haulage vehicle while theaccumulators 60, 62 and 64 are being recharged with fluid. The fluidexhausted from hydraulic conveyor motor 24 flows through conduit 102through fluid inlet 98 to the recharging device 74.

With this arrangement the energy required to actuate the endlessconveyor 18 for discharging the dislodged material from thehaulagecompartment is provided by the recharging device 74 while theaccumulators 60, 62 and 64 are being recharged with hydraulic fluid. Itis now possible with the above described apparatus to quickly andefficiently provide the energy required to propel a mine haulagevehiclefrom a discharge station to a loading station while the haulage vehicleis stopped and dislodged material is being discharged therefrom. Thetime cycle for transporting the dislodged material from the loadingstation to the discharge station is not increased by the rechargingbecause a short period of time is required to unload the vehicle at thedischarge station. It is during that period of time that the fluidpropulsion system is recharged with fluid energy suffrcient to propelthe vehicle at the desired'preselected speeds between the dischargestation and the loading station where another load of the dislodgedmaterial is taken on by the haulage vehicle andtransported from theloading station to the discharge station.

Referring now to FIGS. 5-8, other embodiments of the circuits for thefluid propelled haulage vehicles are illustrated. Similar parts will bedesignated by similar numerals for each of the embodiments illustratedin FIGS. 5-8.

Referring to H6. 5, there are provided a pair of fluid motors 116 and118 mounted on opposite sides of the haulage vehicle 10. The motors 116and 118 are connected through reducers 120 and 122 to drivingconnections 124 and 126. The driving connections 124 are arranged todrive the wheels 14 and 16 on one side of the haulage vehicle and thedriving connections 126 are arranged to drive the wheels 14 and 16 onthe op posite side of the vehicle. Fluid under pressure is supplied tothe motors 116 and 118 from accumulator 128 positioned between thewheels 14 and 16. The fluid under pressure flows through conduit 130 toconduit 132. The conduit 132 is connected to branch conduits 134 and136. The inlets of motors 116 and 118 are, in turn, connected to branchconduits 134 and 136. The outlets of motors 116 and 118 are connected tothe ends of conduit 138. Intermediate the end portions of conduit 138there is a branch conduit 140 that is connected to conduit 142 andconduit 142 conveys-the fluid from motors 116 and 118 into the reservoir144. The conveyor motor 24 has the conduit 142 connected thereto toconvey the fluid from the conveyor drive motor 24 to the reservoir 144.The reservoir 144 has a suitable outlet conduit 146 with a check valve148 therein. The conduit 146 is arranged to be connected to the inletconduit 88 of recharging device 74 previously described. The accumulator128 is recharged with fluid through conduit 150 that has a check valve152 therein. Fluid is conveyed from the recharging device 74 throughconduit 150 to conduit 132 and through conduit 130 into the accumulator128. Fluid from conduit 150 flows through conduit 132 when valve 152 isopened to provide fluid for conveyor drive motor 24 to actuate theendless conveyor 18, dislodging the material therefrom. It should benoted in both of the embodiments illustrated in FIGS. 1 and thatsuitable circuitry is provided to actuate the conveyor drive motor 24 bythe pressurized fluid in the accumulators 60,62 and 64. With the abovearrangement a pair of motors 116 and 118 are provided to drive the pairsof traction wheels on opposite sides of the haulage vehicle and themanner of recharging the accumula tor 128 is similar to that previouslydescribed in reference to the embodiment illustrated in FIGS. 1-4.

Referring to FIG. 6 there is illustrated another embodiment of thehaulage vehicle which includes a recharging pump 154 mounted on thehaulage vehicle. A conduit 156 is connected at one end to the outlet ofpump 154 and at the other end to a branch conduit 158. There is a checkvalve 160 in the conduit 156 to limit the flow of fluid to the directionindicated by the arrow. The conduit 156 has a branch conduit 162 thatconnects the conduit 158 to the fluid side of the accumulator 164. Theconduit 158 is also connected through valve 166 to the conveyor motor24. The conduit 158 also connects the inlet of motor 28 with the branchconduit 162 and the fluid side of accumulator 164 so that fluid underpressure flows from accumulator 164 to the inlet of motor 28. The outletof motor 28 is connected by means of branch conduit 168 to a main returnconduit 170. The return conduit 170 is also connected to the outlet ofconveyor motor 24 and to the reservoir 72. An outlet from reservoir 72is connected by means of conduit 172 to the inlet of pump 154. The drivearrangement for the propelling wheels 14 and 16 in FIG. 6 issubstantially the same as that illustrated in FIG. 1.

At the discharge station there is an electric recharging motor 174 thathas an output shaft 176 connectible through a flexible coupling 178 toan input shaft 180 of recharging pump 154. With the above arrangementthe haulage vehicle 10 as it arrives at the discharge station has therecharging motor 174 coupled to the recharging pump 154 for rechargingor repressurizing the fluid circuit. The motor 174 is energized towithdraw fluid from the reservoir 72 and to convey the fluid to theaccumulator 164 where the fluid displaces the gas within the accumulator164 and repressurizes the circuit. Both the recharging pump 154 andoutput pump 78 in FIGS. 3 and 4 are preferably positive displacementpumps arranged to positively displace the fluid supplied thereto to theoil side of the accumulators. With the above arrangement the rechargingapparatus includes a positive displacement recharging pump 154 mountedon the haulage vehicle and connected in the fluid circuit. An actuatingmeans for the recharging pump 154, preferably an electric rechargingmotor 174, is located at the discharge station. While the vehicle isdischarging the dislodged material from the haulage compartment 12, theelectric recharging motor 174 is connected to the positive displacementrecharging pump 154 on the haulage vehicle. Actuation of the rechargingmotor 174 then recharges the accumulator 164 with the fluid topressurize the same.

Referring to FIG. 7 another embodiment of the fluid propelled haulagevehicle 10 is illustrated. In this embodiment the gear type reducer 34has suitable gearing and clutches to disconnect the reducer from thepropelling wheel drive train to permit the input shaft 182 to serve asan output shaft and drive the fluid actuated motor 28 as a pump tofunction in a manner similar to the positive displacement rechargingpump 154 in the embodiment illustrated in FIG. 6. The output shaft 176of electric motor 174 is connected through coupling 178 to a shaft 184extending from reducer 34 that serves as an input shaft during therecharging of the fluid system. The electric motor 174 through shafts176 and 184 and the gearing within reducer 34, rotates shaft 182 to, inturn, drive the pump-motor 28 as a pump and recirculate fluid from thereservoir 72 to the accumulator 164. The circuit for the fluid issimilar to and operates in substantially the same manner as the circuitpreviously described with reference to the embodiment illustrated inFIG. 6. The drive arrangement for the propelling wheels 14 and 16 inFIG. 7 is substantially the same as that illustrated in FIGS. 1 and 6.

Now referring to FIG. 8 there is illustrated another embodiment of thefluid propelled haulage vehicle in which the gas side of theaccumulators is charged with gas under pressure to increase the fluidpressure on the opposite side of the diaphragm within the accumulator.The hydraulic fluid within the system is transferred from oneaccumulator through the fluid actuated motor to a second accumulator.The accumulator receiving the exhausted fluid is vented to theatmosphere. To recharge the system gas under pressure is supplied to thevented portion of the accumulator containing the fluid to pressurize thefluid within the recharged accumulator.

Referring now to FIG. 8 there are a pair of accumulators 186 and 188associated with the fluid actuated drive motor 28. Another pair ofaccumulators 190 and 192 are associated with the conveyor drive motor24. There is also provided a tank 194 for storage of gas under pressure.The accumulator 186 is connected to the motor 28 by a conduit 196 andbranch conduit 198 on the opposite side of a reversing valve 200. Theaccumulator 188 is connected to the motor 28 by conduit 202 and branchconduit 204 on the opposite side of reversing valve 200. Depending onthe position of the reversing valve 200, fluid under pressure may flowfrom either accumulator 186 or 188 through the conduits associatedtherewith to the input side of the motor 28. The output side of themotor is connected through the reversing valve 200 and respectiveconduits to the other of the associated accumulators. With thisarrangement, for example when fluid under pressure is in accumulator186, it flows through conduit 196, valve 200, and conduit 198 to theinput of fluid actuated motor 28. The fluid flows from fluid actuatedmotor 28 through conduit 204, valve 200 and conduit 202 to the oil sideof accumulator 188. The gas side of accumulator 188 has been vented toatmosphere through valve 212 and thus provides a reservoir for the fluiddisplaced from accumulator 186. When the fluid system is to berecharged, gas under pressure flows through conduit 206 at the fixeddischarge station through check valve 208 on the vehicle to conduit 210.Assuming that accumulator 188 is filled with fluid, the valve 212 inconduit 214 is opened to permit gas under pressure to flow into the gasside of the accumulator to pressurize the fluid therein. At the sametime, the valve 216 associated with accumulator 186 is closed and thegas side of accumulator 186 is vented to atmosphere. The gas storagetank 194 is also pressurized through conduit 210 to maintain a pressurewithin conduits 214 and 210 that communicate with the gas side of bothaccumulators 186 and 188 and the gas storage tank 194. To utilize thefluid under pressure in accumulator 188, the valve 200 is reversed andthe fluid under pressure flows through conduit 202, valve 200 andconduit 198 to the inlet of motor 28. The fluid flows from fluidactuated motor 28 through conduit 204, valve 200 and conduit 196 to theaccumulator 186. with this cycle the gas side of accumulator 186 isvented to atmosphere to permit the accumulator 186 to serve as areservoir. On

recharging the vehicle 10 at the discharge station the valve 216 is opento permit gas under pressure to flow into the gas side of accumulator186 and pressurize the fluid therein. Additional gas under pressure isprovided from tank 194 and may be connected to the gas side of theaccumulator containing the oil under pressure therein.

The accumulators 190 and 192 are similarly connected to conveyor drivemotor 24 through a reversing valve 218 and function in a manner similarto the previously described pair of accumulators 186 and 188. The drivearrangement for the propelling wheels 14 and 16 is substantially thesame as that previously describedwith reference to FIGS. 1 and 6.

It will 'be appreciated with the previously described embodiments thatit is now possible to transport material under ground with a haulagevehicle that utilizes fluid under pressure as the propelling medium. Thefluid may be repressurized at the fixed discharge station by eitherrecycling the fluid from a reservoir through an external pump mounted onthe recharging device or through a pump mounted on the haulage vehicle.Further, a gas may be employed as the recharging medium to repressurizethe fluid in the accumulators. According to the provisions of the patentstatutes, the principle, preferred construction and mode of operation ofthe invention have been explained and what is considered to representits best embodiment has been illustrated and described. However, itshould be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically illustratedand described.

lclaim:

1. In an underground haulage vehicle the combination comprising,

a mobile body having a material haulage compartment,

an endless conveyor positioned in said material haulage compartment,

pairs of front and rear wheels, certain of said wheels being tractionwheels,

fluid actuated drive means mounted on said mobile body,

mechanical driving connections between said fluid actuated drive meansand said traction wheels,

. propelling fluid storage means mounted on said mobile body andconnected to said fluid actuated drive means, propelling fluid in saidpropelling fluid storage means,

pressure means on said mobile body arranged to pressurize saidpropelling fluid in said propelling fluid storage means, said pressuremeans operable to propel said propelling fluid through said fluidactuated drive means to drive said fluid actuated drive means and saidtraction wheels through said mechanical driving connections, rechargingmeans mounted separately from said haulage vehicle operable toperiodically repressurize said pressure means second fluid actuateddrive means connected to said endless conveyor for propelling saidendless conveyor within said material haulage compartment, and meansconnecting said recharging means to said second fluid actuated drivemeans to drive said second fluid actuated drive means. 2. An undergroundhaulage vehicle as set forth in claim 1 in which,

said pairs of front and rear wheels are traction wheels, said fluidactuated drive means including a hydraulic motor mounted on one side ofsaid haulage compartment and connected through said mechanical drivingconnections to all of said traction wheels. 3. An underground haulagevehicle as set forth in claim 1 in which,

said fluid actuated drive means includes a pair of hydraulic motors eachdrivingly connected through mechanical driving connections to a pair oftraction wheels. 4. An underground haulage vehicle as set forth in claim1 which includes, a pump mounted on said mobile body, conduit meansconnecting said pump to said fluid storage means, said recharging meansincluding drive means connectible' to said pump for conveying propellingfluid into said propelling fluid storage means.

5. An'underground haulage vehicle as set forth in claim 1 in which,

said fluid actuated drive means includes pump means, said rechargingmeans including means separate from said haulage vehicle operable todrive said pump means of said fluid actuated means to recharge saidpressure means. 6. An underground haulage vehicle as set forth in claim1 in which,

said fluid storage means includes an accumulator with a flexible walltherein forming separate liquid and gas compartments,

means. 7. An underground haulage vehicle as set forth in claim 1 inwhich,

said fluid storage means includes a pair of accumulators, fluid conduitmeans connecting said accumulators in series with said fluid actuateddrive means, said propelling fluid operable to flow from one of saidaccumulators through said fluid actuated drive means to said otheraccumulator, said recharging means operable to pressurize said fluid ina selected one of said accumulators.

II i i l

1. In an underground haulage vehicle the combination comprising, amobile body having a material haulage compartment, an endless conveyorpositioned in said material haulage compartment, pairs of front and rearwheels, certain of said wheels being traction wheels, fluid actuateddrive means mounted on said mobile body, mechanical driving connectionsbetween said fluid actuated drive means and said traction wheels,propelling fluid storage means mounted on said mobile body and connectedto said fluid actuated drive means, propelling fluid in said propellingfluid storage means, pressure means on said mobile body arranged topressurize said propelling fluid in said propelling fluid storage means,said pressure means operable to propel said propelling fluid throughsaid fluid actuated drive means to drive said fluid actuated drive meansand said traction wheels through said mechanical driving connections,recharging means mounted separately from said haulage vehicle operableto periodically repressurize said pressure means second fluid actuateddrive means connected to said endless conveyor for propelling saidendless conveyor within said material haulage compartment, and meansconnecting said recharging means to said second fluid actuated drivemeans to drive said second fluid actuated drive means.
 2. An undergroundhaulage vehicle as set forth in claim 1 in which, said pairs of frontand rear wheels are traction wheels, said fluid actuated drive meansincluding a hydraulic motor mounted on one side of said haulagecompartment and connected through said mechanical driving connections toall of said traction wheels.
 3. An underground haulage vehicle as setforth in claim 1 in which, said fluid actuated drive means includes apair of hydraulic motors each drivingly connected through mechanicaldriving connections to a pair of traction wheels.
 4. An undergroundhaulage vehicle as set forth in claim 1 which includes, a pump mountedon said mobile body, conduit means connecting said pump to said fluidstorage means, said recharging means including drive means connectibleto said pump for conveying propelling fluid into said propelling fluidstorage means.
 5. An underground haulage vehicle as set forth in claim 1in which, said fluid actuated drive means includes pump means, saidrecharging means including means separate from said haulage vehicleoperable to drive said pump means of said fluid actuated means torecharge said pressure means.
 6. An underground haulage vehicle as setforth in claim 1 in which, said fluid storage means includes anaccumulator with a flexible wall therein forming separate liquid and gascompartments, said pressure means comprising a compressible gas withinsaid accumulator gas compartment operable to exert a pressure on saidpropelling fluid in said liquid compartment, a reservoir mounted on saidvehicle, fluid connections between said fluid actuated motor and saidreservoir operable to convey said propelling fluid from said fluidactuated motor to said reservoir, said recharging means operable toconvey said propelling fluid from said reservoir to said liquidcompartment of said accumulator and displace said compresible gas insaid accumulator to thereby increase the pressure of said pressuremeans.
 7. An underground haulage vehicle as set forth in claim 1 inwhich, said fluid storage means includes a pair of accumulators, fluidconduit means connecting said accumulators in series with said fluidactuated drive means, said propelling fluid operable to flow from one ofsaid accumulators through said fluid actuated drive means to said otheraccumulator, said recharging means operable to pressurize said fluid ina selected one of Said accumulators.